JP6619277B2 - Heat dissipation member and module using the same - Google Patents

Description

  The present invention relates to a heat radiating member and a module using the same.

  In recent years, with the increase in performance of industrial equipment such as robots and motors, the amount of heat generated from electronic circuits including semiconductor elements has increased. In order to dissipate this heat efficiently, a heat radiating member in which a conductor layer such as a copper plate is bonded onto a ceramic substrate having good heat conduction is used.

  An electronic circuit such as a semiconductor element is mounted on the surface of a conductor layer of such a heat radiating member directly or via a bonding layer such as Ni plating to form a module. Such modules are used in welding machines, train drive units, electric vehicles, fuel cells, and the like, and are required to have durability and further miniaturization under severe environmental conditions in a relatively high temperature atmosphere.

  The following Patent Document 1 aims to improve durability in a high temperature environment, and in order to suppress thermal stress caused by a difference in thermal expansion between the ceramic substrate and the conductor layer, a thin portion is formed at the end of the copper plate. A heat-dissipating member formed with is described.

Japanese Patent Laid-Open No. 01-59986

  In the heat radiating member of Patent Document 1, a thin portion having a recessed surface on the side where a semiconductor element or the like is mounted is formed over the entire periphery of the copper plate. Since a semiconductor element or the like cannot be mounted on this thin portion, the area of the conductor layer and the ceramic substrate is larger overall by the thin portion than the area of the semiconductor element, and the area of the ceramic substrate is correspondingly large. As a result, there is a problem that the overall size becomes large. As described above, in the conventional heat dissipating member, it is difficult to simultaneously realize downsizing and improvement in durability by suppressing thermal stress. The present invention aims to solve the above problems.

A heat dissipation member according to an embodiment of the present invention is a heat dissipation member including an insulating substrate and a conductive plate positioned on the insulating substrate, the conductive plate facing the insulating substrate. and one surface, and a second surface located opposite the first surface, the contour of the first surface viewed from the front is a polygonal shape having a plurality of corners and a plurality of side portions, said The thickness of the second region, which is the central portion of the side portion, is thinner than the thickness of the second other region other than the second region, and the second other region is between the second region and the corner portion. The region is located.

A heat dissipation member according to an embodiment of the present invention is a heat dissipation member including an insulating substrate and a conductive plate positioned on the insulating substrate, the conductive plate facing the insulating substrate. and one surface, and a second surface located opposite the first surface, the contour of the first surface viewed from the front is a polygonal shape having a plurality of corners and a plurality of side portions, said The thickness of the first region including the corners and the thickness of the second region, which is the central portion of the side portion, are thinner than the thickness of the third other region other than the first region and the second region, The third other region is located between the region and the corner portion.

  Moreover, the module characterized by having either the heat radiating member of this embodiment mentioned above and the electronic component mounted in the said other main surface of the said electrically conductive plate is provided together.

  The heat dissipating member of the present embodiment has a structure that can cope with downsizing and has high durability because there is little concentration of thermal stress.

It is the schematic which shows an example of the heat radiating member which concerns on this embodiment, (a) is a schematic top view, (b) is a schematic side view. (A) is a schematic perspective view of the state which cut out some heat dissipation members shown in FIG. 1, (b) is the elements on larger scale of (a). It is sectional drawing which expands and shows a part of heat radiating member shown to FIG. 1 and FIG. It is a figure which shows the thermal stress distribution simulated using the three-dimensional model, (a) is a figure which shows the simulation result about the conventional heat radiating member, (b) is only an insulating board | substrate among the models of (a). The figure shown, (c) is a figure which shows the simulation result about this embodiment shown in FIGS. 1-3, (d) is the figure which showed only the insulating board | substrate among the models of (c). (A) And (b) is a partial expansion perspective view which shows the other example of the thermal radiation member which concerns on this embodiment, respectively. (A)-(e) is a schematic sectional drawing explaining an example of the manufacturing method of the thermal radiation member shown in FIGS. 1-3.

  The heat dissipation member according to the first embodiment includes an insulating substrate and a conductive plate located on the insulating substrate. The conductive plate has a first surface facing the insulating substrate and a second surface positioned opposite to the first surface, and the outline of the first surface in front view has a plurality of corner portions and a plurality of corners. The thickness of the first region including the corners is thinner than the thickness of the first other region other than the first region. The heat radiating member according to the first embodiment has a structure that can cope with downsizing by satisfying the above-described configuration, and has relatively low concentration of thermal stress and high durability.

  The heat dissipation member according to the second embodiment includes an insulating substrate and a conductive plate located on the insulating substrate. The conductive plate has a first surface facing the insulating substrate and a second surface positioned opposite to the first surface, and the outline of the first surface in a front view has a plurality of corner portions and a plurality of corners. The thickness of the second region, which is the central portion of the side portion, is thinner than the thickness of the second other region other than the second region. The heat radiating member according to the second embodiment has a structure that can cope with downsizing by satisfying the above-described configuration, and has relatively low concentration of thermal stress and high durability. In addition, the heat radiating member which concerns on 1st Embodiment and 2nd Embodiment is later mentioned using FIG.

  The heat radiating member according to the third embodiment will be described in detail with reference to the drawings. In addition, the part of the same structure name as the said description has the same effect.

FIG. 1 is a schematic diagram illustrating an example of a heat dissipation member according to the third embodiment. Fig.1 (a) is a schematic top view of a heat radiating member, FIG.1 (b) is a schematic sectional drawing of a heat radiating member. 2A is a schematic perspective view of a state where a part of the heat radiating member shown in FIG. 1 is cut out, and FIG. 2B is a partially enlarged view of FIG. FIG. 3 is an enlarged cross-sectional view of a part of the heat dissipation member shown in FIGS. 1 and 2. In addition, in the following description, when it is common to 1st-3rd embodiment, it describes as "this embodiment."

  The heat radiating member 20 includes an insulating substrate 2 and a conductive plate 4 positioned on the insulating substrate 2. The conductive plate 4 has a first surface 4B facing the insulating substrate 2 and a second surface 4A located opposite to the first surface 4B, and a plurality of contours of the first surface 4B in front view are provided. Of the first region 4α including the corner portion 42 and the thickness of the second region 4β which is the central portion of the side portion 41 are the first region 4α. The thickness is smaller than the thickness of the other region 4γ (third other region) other than the second region 4β.

  In FIG. 3, the conductive plate 4 is illustrated as being bonded to the insulating substrate 2 via the bonding layer 6, but may be directly bonded. Further, the shape of the conductive plate 4 (the outline of the first surface 4B) is a quadrangular shape when viewed from above. Further, the conductive plate 4 has four side portions 41 and a total of four corner portions 42 disposed between the two side portions 41 orthogonal to each other. Here, the conductive plate 4 has a vertical dimension of 36 mm in FIG. 1 and a horizontal dimension of 48 mm in FIG. 1, for example. The corner portion 42 includes a vertex where the two side portions 41 abut, and corresponds to, for example, a range surrounded by a circumference having a radius of 1 mm around the vertex in the conductive plate 4 having the above-described size. The first region 4α has a right-angled isosceles triangle shape in which two sides are orthogonal in a top view. In the conductive plate 4 having the above-described size, the length in two orthogonal sides is, for example, 3.5 mm. In addition, the second region 4β that is the central portion of the side portion 41 is included in a range of a radius of 15 mm with the center position C of the side portion 41 as the center, for example. In the example shown in FIGS. 1A and 2A, the second region 4β has a partial circular shape surrounded by a partial arc and a straight line when viewed from above. The shape and size of the conductive plate 4 and the shapes and sizes of the first region 4α and the second region 4β are not limited to the examples described above.

  In the third embodiment, the thickness of the first region 4α and the thickness of the second region 4β are thinner than the other region 4γ (third other region), which is another region. Thermal stress caused by the difference in thermal expansion between the insulating substrate 2 and the conductive plate 4 generated in the two regions 4β is reduced. Moreover, peeling of a corresponding part is also suppressed by the reduction of thermal stress.

  On the other hand, the other region 4γ other than the first region 4α and the second region 4β is relatively thick, and the entire other region 4γ can be used as a region where an electronic circuit such as a semiconductor element can be mounted. The heat radiating member 20 of the present embodiment can reduce the thermal stress only in the region where the thermal stress occurs (the first region 4α and the second region 4β), and has a region where an electronic circuit such as a semiconductor element can be mounted. Since it is a structure, it can respond to size reduction of the thermal radiation member 20. FIG.

  The heat radiating member 20 generates relatively large thermal stress in the first region 4α including the corner portion 42 and the second region 4β including the center position C. This will be described with reference to FIG.

  4A and 4B are diagrams showing the distribution of thermal stress simulated using a three-dimensional model. FIG. 4A is a diagram showing a simulation result of a conventional heat radiating member, and FIG. 4B is a diagram of the model of FIG. The figure which showed only the insulating board | substrate, (c) is a figure which shows the simulation result about the thermal radiation member shown in FIGS. 1-3, (d) is the figure which showed only the insulating board | substrate among the models of (c). is there. Note that the difference between the conventional heat dissipating member shown in FIGS. 4A and 4B and the heat dissipating member of the third embodiment is the presence or absence of the first region.

4A to 4D show a part of a region including a corner portion. 4 (a) to 4 (d) are analysis results by a so-called finite element method (FEM), and the entire finite element model shown in FIGS. 4 (a) and 4 (c) is obtained from a predetermined temperature T (° C.). The stress in the state changed to T-100 (degreeC) is shown. FIG. 4 shows the distribution of stress concentrated when the temperature is reduced in a part of the region including the corners.

  In a model having a conductive plate having a uniform thickness as a whole without having a thin portion at the corner as shown in FIG. 4A, it corresponds to the corner in FIGS. 4A and 4B. Since the color of the portion is dark, it can be seen that a large thermal stress is concentrated on the insulating substrate in the portion including the corner portion. On the other hand, in the model reproducing the heat radiating member of the third embodiment shown in FIG. 4C, the stress concentration at the corners is relaxed as can be seen from FIG. When a large stress is generated locally, this is the starting point, and peeling of the conductive plate, cracking of the insulating substrate, and the like easily progress. In the heat dissipation member of the third embodiment, since the thickness of the first region including the corners is thinner than the other regions, such stress concentration is suppressed, so that the overall durability of the heat dissipation member 20 is improved. (The same applies to the first embodiment).

  Although not shown, the same simulation is performed for the second region corresponding to the central portion of the side portion, and it is confirmed that stress is concentrated on the second region. In the second region, stress tends to concentrate particularly when the temperature is raised. The heat dissipating member of the present embodiment can alleviate both the thermal stress caused by the temperature rise and the thermal stress caused by the temperature fall.

  In the present embodiment, the first region 4α and the second region 4β and the other region 4γ (third other region) have a step portion 50 (third step portion), and the step portion 50 and the other region 4γ. And may be connected in a curved line. Such a configuration will be described with reference to FIG. The stepped portion 50 and the other region 4γ are connected in a curved line because the second connecting portion 52 between the stepped portion 50 and the other region 4γ is curved in a sectional view as shown in FIG. That means. Further, at least any one of the step portion 50, the first region 4α, and the second region 4β may be connected in a curved line. This configuration means that the first connection portion 51 between the step portion 50 and the first region 4α and the second region 4β is curved in a cross-sectional view as shown in FIG.

  As can be seen from FIG. 4C, relatively large stress tends to concentrate on the first connection part 51 and the second connection part 52. By setting the first connection part 51 and the second connection part 52 to have a curved shape in a cross-sectional view, the degree of stress concentration on the first connection part 51 and the second connection part 52 can be alleviated, and the conductivity accompanying the stress concentration can be reduced. The deterioration of the plate 4 itself is also suppressed. In addition, although it is preferable to be provided in both the first region 4α and the second region 4β, the present invention is not limited to this, and it is provided corresponding to only one of the first region 4α and the second region 4β. May be.

The insulating substrate 2 is a ceramic substrate whose main component is, for example, silicon nitride (Si ₃ N ₄ ). The insulating substrate 2 may be a ceramic substrate mainly composed of alumina (Al ₂ O ₃ ), aluminum nitride (AlN), etc. in addition to silicon nitride (Si ₃ N ₄ ), and is required. What is necessary is just to comprise with the material selected suitably according to the some heat transfer characteristic and thermal expansion coefficient. In the present embodiment, the insulating substrate 2 has a thickness of 0.2 to 1 mm, for example.

  As the bonding layer 6, for example, a so-called Ag—Cu—Ti brazing material or the like may be used. For example, a composition containing 15 to 50% by weight of Cu, 1 to 10% of at least one active metal selected from Ti, Zr, Hf and Nb and the balance substantially consisting of Ag is dispersed in an organic solvent. The bonding composition paste thus prepared may be used. The thickness of the bonding layer 6 is, for example, 0.005 to 0.05 mm.

The conductive plate 4 is made of, for example, a metal plate whose main component is copper (Cu). The metal plate is patterned into a predetermined shape in plan view and is divided into a plurality of portions. Note that the bonding layer 6 is not necessarily provided. For example, the conductive plate 4 made of copper and the insulating substrate 2 made of ceramics may be bonded by a so-called direct bonding method. For example, a so-called copper direct bonding method (DBC method: Direct Bonding Copper method) in which a copper plate is directly bonded onto a ceramic substrate using a eutectic liquid phase such as Cu—Cu ₂ O may be used.

  In the present embodiment, the total thickness T of the conductive plate 4 and the bonding layer 6 is, for example, 0.45 to 1.5 mm. Further, the width B of the first region 4α or the second region 4β shown in FIG. 3 is, for example, 1 to 5 mm, and the height H of the first region 4α or the second region 4β is, for example, 0.05 to 0.3 mm. . When each numerical value is in the above range, it is preferable in that stress concentration is easily relaxed and damage to the heat radiation member 20 due to stress is easily suppressed.

  FIG. 5A is a heat radiating member according to the first embodiment, and FIG. 5B is a heat radiating member according to the second embodiment. In FIG. 5, about the same part as embodiment shown in FIGS. 1-3, it represents with the same code | symbol as FIGS. 1-3, and the heat radiating member shown to FIG. The reference numeral “22” is attached to the member.

  The heat radiating member 21 shown in FIG. 5A differs from the third embodiment shown in FIGS. 1 to 3 in that it does not have the second region 4β. Moreover, the heat radiating member 22 shown in FIG.5 (b) differs in the point which does not have 1st area | region 4 (alpha) compared with 3rd Embodiment shown in FIGS. 1-3. The heat dissipating member 21 and the heat dissipating member 22 have a structure that can cope with downsizing and have relatively low concentration of thermal stress and high durability. The heat dissipation member 21 is preferably used for a device used at a relatively low temperature, and the heat dissipation member 22 is preferably used for a device used at a relatively high temperature.

  Further, when the heat dissipation member 21 and the heat dissipation member 22 do not have the first region 4α or the second region 4β and have the same area in the top view of the conductive plate 4, the heat dissipation member 20 of the third embodiment. In addition, since a mountable area of an electronic circuit such as a semiconductor element is large, a large semiconductor element can be mounted.

  Needless to say, also in the heat radiating member 21 and the heat radiating member 22, it is preferable that the first region 4α and the other region 4γ, and the second region 4β and the other region 4γ are connected in a curved shape.

  Next, a module according to this embodiment having any one of the heat radiation members 20 to 22 and an electronic component mounted on the other main surface 4A of the conductive plate 4 will be described. The module of the present embodiment can reduce the thermal stress only in the region where the thermal stress occurs, and has a region where the electronic component such as a semiconductor element can be mounted on the other main surface 4A of the motorized plate 4. Therefore, the overall area including the insulating substrate 2 can be made relatively small and compact with respect to electronic components such as semiconductor elements to be mounted. The heat dissipating members 20 to 22 are relatively small and compact, while the portion where the stress is concentrated is selectively thinned to reduce the concentration of the thermal stress and have high durability.

  An example of the manufacturing method of the heat radiating member of this embodiment is demonstrated with reference to Fig.6 (a)-(e). In addition, the code | symbol of "20" which shows the heat radiating member of 3rd Embodiment is attached | subjected to the heat radiating member shown in FIG.6 (e).

First, as shown in FIG. 6A, a copper plate 30 is bonded to both main surfaces of an insulating substrate 2, which is a ceramic substrate mainly composed of silicon nitride (Si ₃ N ₄ ), for example. In bonding, a bonding agent, which is a precursor of the bonding layer 6, is applied to both main surfaces of the insulating substrate 2, and the copper plate 30 is placed in contact with both main surfaces of the insulating substrate 2. Heat. In the present embodiment, the copper plates 30 are brought into contact with the two main surfaces of the insulating substrate 2, and pressure is applied from the upper side and the lower side in the drawing. In this state, the whole is housed in a heating furnace, and heated and heated at 700 to 950 ° C. for 5 to 30 minutes in a vacuum to perform a bonding process.

  Next, as shown in FIG. 6B, an etching mask 71 having a predetermined shape made of a resist or the like is selectively applied to the surface of the copper plate 30, and then the ferric chloride solution as an etchant (etchant) is applied. Immerse the whole thing. In this etching, the copper plate 30 is selectively etched. In this etching, so-called half-etching is performed in which the copper plate 30 is not etched until the surface of the insulating substrate 2 appears, and the copper plate 30 is etched only halfway in the thickness direction.

  Next, after removing the etching mask 1 formed at the time of etching in FIG. 6B, the etching mask 71 formed at the time of the previous etching is formed on the surface of the copper plate 30 as shown in FIG. 6C. Etching masks 72 having different sizes are formed. The etching mask 72 is slightly smaller than the etching mask 71 in a top view and is a mask having the same shape as the etching mask 71.

  Next, as shown in FIG. 6D, the whole is immersed in a ferric chloride solution as an etchant (etchant) with the etching mask 72 formed. In this etching, the copper plate 30 is etched in the depth direction until the surface of the insulating substrate 2 appears. In this etching, the etching proceeds so that the step between the recess formed at the previous etching and the surface of the copper plate 30 is widened, and the conductive plate 4 having a step shape as shown in FIG. 3 is formed. . Next, the remaining etching mask 72 is removed, and the heat radiating member 20 as shown in FIG. 6E can be obtained.

  As mentioned above, although the heat radiating member of this invention and the module using the same were demonstrated, the heat radiating member of this invention and the module using the same are not limited to the said Example, It does not deviate from the summary of this invention. Of course, various improvements and modifications may be made within the scope.

2 Insulating substrate 4 Conductive plate 6 Bonding layer 4α First region 4β Second region 4γ Other region 4A Second surface 4B First surface 41 Side portion 42 Corner portion 20 Heat radiation member 50 Step portion 51 First connection portion 52 Second connection Part

Claims (9)

A heat-dissipating member comprising an insulating substrate and a conductive plate located on the insulating substrate,
The conductive plate has a first surface facing the insulating substrate, and a second surface located opposite to the first surface;
The outline of the first surface in a front view is a polygonal shape having a plurality of corners and a plurality of sides.
The thickness of the second region, which is the central portion of the side portion, is thinner than the thickness of the second other region other than the second region, and the second other region is between the second region and the corner portion. A heat radiating member, wherein the region is located. 2. The second region and the second other region have a second step portion, and the second step portion and the second region are connected in a curved line. The heat radiating member as described in 2.   The second region and the second other region have a second step portion, and the second step portion and the second other region are connected in a curved line. The heat radiating member according to claim 1 or 2. A heat-dissipating member comprising an insulating substrate and a conductive plate located on the insulating substrate,
The conductive plate has a first surface facing the insulating substrate, and a second surface located opposite to the first surface;
The outline of the first surface in a front view is a polygonal shape having a plurality of corners and a plurality of sides.
The thickness of the first region including the corner portion and the thickness of the second region which is a central portion in the side portion are thinner than the thickness of the third other region other than the first region and the second region, The heat radiating member, wherein the third other region is located between two regions and the corner portion.   At least one of the first region and the second region and the third other region have a third step portion, and the third step portion and the third other region are curved. The heat-radiating member according to claim 4, wherein the heat-radiating member is connected in a shape.   At least one of the first region and the second region and the third other region have a third step portion, and the third step portion, the first region, and the second region. 6. The heat radiating member according to claim 4, wherein at least one of the two is connected in a curved line.   The heat insulating member according to claim 1, wherein the insulating substrate is made of ceramics.   The heat radiating member according to claim 1, wherein a main component of the conductive plate is copper.   A module comprising an electronic component on the conductive plate in the heat dissipating member according to claim 1.